Data Quality Assessment

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 Data Quality Assessment

GIS 5935 Special Topics in GIS 
Lab 3

Student Learning Outcomes:
  • Determine the completeness of road networks
  • Be able to summarize analysis in textual, visual, and numerical terms

The goal of this exercise was to determine which of two datasets was more complete. 

The total length of road for each data set was calculated per grid cell and then compared. Below is a brief description of the analysis steps:

    1. Clip

      1. Clip both road layer to the area of the grid to eliminate road sections that will not be counted. 

    2. Intersect

      1. This tool divided up road sections that crossed grid boundaries while keeping all road information in one layer. I originally used the split tool, but this required additional geoprocessing that seemed overly complicated for the task at hand. 

    3. Summarize Within

      1. This tool identified and produced a sum of road lengths per grid cell providing very conveniently formatted data to work with. The table had the grid cod and a sum of the length of all the roads within that grid. 

    4. Export table to Excel

      1. Tables for both excel files were used to calculate the percentage difference and the number of instances where one road file was larger than the other (TIGER vs Street Centerlines)

    5. Edit table

      1. One the percentages were obtained in excel I transferred them to the Grid attribute table via simple copy and paste



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